Detection of Listeria innocua in the dairy processing chain: resistance to antibiotics and essential oils

Abstract

Listeria monocytogenes is a food pathogen responsible for many foodborne disease outbreaks. Listeria innocua is similar to L. monocytogenes, could be considered biologically similar to L. monocytogenes and could be used to predict its behavior. The aims of this work were to isolate Listeria spp. in dairy processing plants, perform genotypic characterization of virulence, evaluate the antimicrobial resistance profile, and verify the sensitivity of the strains to essential oils. Sampling was held in six dairy processing plants in the region of Campinas, Brazil. Seventeen Listeria innocua strains were isolated, all negative for virulence genes inlA, inlB, inlC, inlJ, actA, plcA, and plcB. The strains were resistant to kanamycin (5.9%), penicillin (11.8%), ampicillin (11.8%), cefoxitin (58.8%), clindamycin (76.50%) and oxacillin (100%). The susceptibility of the strains to commercial essential oils (Rosemarinus officinalis, Cymbopogon citratus, Eucalyptus citirodora, Mentha piperita, Piper nigrum, Vetiveria zizanioides, Cymbopogon nardus, Cymbopogon martinii and Pogostemon cablin) was evaluated by Minimum Inhibitory Concentration (MIC) test. The results showed Cymbopogon citratus, Cymbopogon martini, Cymbopogon nardus and Mentha piperita oils were most efficient. The resistance of Listeria innocua isolated in dairy processing plants is worrisome, and the use of essential oils could be an alternative for development of new drugs and products.

Unraveling the antimicrobial activity of nutmeg and turmeric essential oils against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella spp.

“…Standard strains of S. aureus (ATCC 25923), E. coli (ATCC 25922), L. monocytogenes (ATCC 7644), and Salmonella Tiphymurium (ATCC 14028) were used. In addition, two wild-type strains of each bacteria isolated from food in previous studies (da Rosa et al, 2022;da Silva Cândido et al, 2020;Morasi et al, 2022) were stored at the Food Microbiology Laboratory II (UNICAMP) with the following coding: S. aureus A1, S. aureus 94, E. coli 46, E. coli 116, Listeria innocua 4445, L. innocua 4422, Salmonella 1R, and Salmonella 2R.…”

Prevalence and Antimicrobial Resistance Pattern of Listeria Monocytogenes in Ready t o Eat Foods in Tamil Nadu, India

“…Up to the present time, the genus Listeria has been identified with 20 species of bacteria. Some of the prominent species L. monocytogenes have the most significant impact on public health because of their ability to cause listeriosis both in humans and animals (8) . The conventional method to diagnose Listeria through isolation and biochemical characterization is time -consuming and molecular approaches like PCR-specific techniques for the diagnosis of L. monocytogenes target specific genes (9) .…”